These singing bowls are all completely made by hand. The 'etching' art on the Himalayan Art bowls, and the carvings on the Zen Bowls, are done by artists in Nepal. All are made using a mix of metals; copper, bronze, brass, tin, zinc, and lead - but the Copper Conductor bowl is primarily made of (you guessed it!) copper.
Handmade singing bowls are of a much higher quality than factory made bowls and this is greatly reflected in their sound quality. With handmade bowls, the sound is much more deep - it is rich with more overtones, and the bowl's resonance lasts for a prolonged length of time.